Glass lamination process
View Patent ↗Glass laminates are prepared using low-water content plastic interlayer material, such as polyvinylbutyral interlayer sheets, by a process employing nip roll de-airing, and high temperature finishing at atmospheric pressure.
1. A process for making a laminate comprising: positioning a plastic material selected from the group consisting of polyvinyl butyral and ionomeric resins, having a moisture content below 0.35 percent by weight of the plastic material, opposite at least one rigid substrate;
pre-heating the at least one rigid substrate, or the plastic material, or any combination thereof, to a tacking temperature of about 40° C. to about 130° C.;
tacking the plastic material and the at least one rigid substrate through a nip roll in a short term pressure application having a duration of less than about 15 minutes, without using vacuum de-airing, to form a pre-laminate having partial adhesion of plastic material to the substrate;
heating the pre-laminate at a temperature of about 125° C. to about 220° C. for a time effective to relax stresses in and dissolve air into the plastic material and finish bond the plastic material to the at least one rigid substrate;
wherein said heating is conducted at a pressure ranging from about 1 atmosphere to about 3 atmospheres;
without a subsequent or preceding autoclave step at a pressure above about 3 atmospheres.
2. The process of claim 1 , for making a laminate wherein the positioning step further comprises:
interposing the plastic material, having a moisture content below 0.35 percent by weight of the plastic material, between two rigid substrates.
3. The process of claim 1 , wherein said pre-heating is at a temperature ranging from about 70° C. to about 100° C.
4. The process of claim 1 , wherein the short term pressure application is for a duration of about 0.02 to about 100 seconds.
5. The process of claim 4 , wherein the short term pressure application is for a duration of about 0.04 to about 50 seconds.
6. The process of claim 2 , wherein the short term pressure application is at a pressure of at least about 5 psi.
7. The process of claim 2 , wherein the heating is for a time ranging from about 0.5 minutes to about 180 minutes.
8. The process of claim 7 , wherein the heating is for a time ranging from about 2 to about 60 minutes.
9. The process of claim 1 , wherein said heating is conducted at a pressure of about 1 atmosphere.
10. The process according to claim 2 , wherein said plastic material is a polyvinylbutyral sheet.
11. The process according to claim 10 , wherein at least one of said substrates is glass.
12. The process according to claim 10 , wherein said polyvinylbutyral sheet has a moisture content below about 0.30 percent by weight of said polyvinylbutyral sheet.
13. The process according to claim 12 , wherein said moisture content is between about 0.01 and about 0.20 percent by weight.
14. The process according to claim 13 , wherein said moisture content is between about 0.03 and about 0.18 percent by weight.
15. The process according to claim 2 , wherein multiple layers of plastic material are sandwiched between two rigid substrates.
16. The process according to claim 1 , wherein said short term pressure application is at a pressure of about 2 to about 2000 pounds per linear inch.
17. The process according to claim 15 , wherein at least two of said multiple layers of plastic material comprise different plastic materials.
18. A process for making a laminate comprising:
interposing a polyvinylbutyral sheet, having a moisture content between about 0.01 and about 0.20 percent by weight, between two rigid substrates;
tacking the polyvinylbutyral and the substrates together and sealing edges to form a pre-laminate;
passing the prelaminate through a nip-roll short term pressure application without using vacuum de-airing for a duration of about 0.02 to about 100 seconds; and
heating at a temperature of about 150° C. to about 220° C. at a pressure of about 1 atmosphere to about 3 atmospheres for about 0.5 minutes to about 180 minutes to bond the polyvinylbutyral to the substrates and form a laminate without a subsequent or preceding autoclave step at a pressure above about 3 atmospheres.
19. The process of claim 18 , wherein said heating is conducted at a pressure of about 1 atmosphere.
20. The process according to claim 18 , comprising the step of conditioning said polyvinylbutyral sheet to reduce the moisture content to a range of about 0.01 to about 0.20 percent by weight of said polyvinylbutyral sheet.